DxOMark said the Sony FE 100-400mm GM has very high levels of sharpness, low fringing and vignetting and it is the Sharpest Telephoto Zoom Lens!

Conclusion from DxOMark:

Telephoto zoom lenses like this tend to be quite large and unwieldy, and are inclined to be sharper at the shorter end of the zoom range. They also often have troublesome chromatic aberration that contributes to the decline in image quality, particularly at the longer end (where you need it the most).